Inspection Procedures - TB-1-1520-237-20-1710003

TB 1-1520-237-20-171

8. Inspection Requirements. Annotate on DA Form 2408-13, for each H-60 aircraft, that an inspection and removal of

suspect bolts is required IAW UH-60-96-ASAM-03, paragraph 9, within the next 100 flight hours.

9. Inspection Procedures. Inspection can be performed during any maintenance action that allows access to the main

rotor shaft nut bolts (S6110-21085-004, TM 1-1520-237-23P, figure 319, item 17). To get access to the main rotor shaft

nut bolts the following procedures can be used.

CAUTION

Damage to main rotor head assembly will result if metallic scrapers are used to clean sealing

compound from components. Do not use metallic items to remove sealant.

Clean sealant from bifilar cover using non-metallic scraper.

Remove bolts. washers and bifilar cover (TM 1-1520-237-23 figure 5-1).

If de-ice kit is installed, disconnect and remove main rotor blade de-ice distributor, slipring assembly and

tube (TM 1-1520-237-23 paragraph 12.7).

Visually inspect the head of each of the 12 main rotor shaft nut bolts for the letter "M" marking.

NOTE

These bolts do not have part number markings and may also be painted yellow. Bolts with a part

number marking and an "M" stamped on the head, are not suspect and shall remain installed.

(1) If the letter "M" is not present, or a part number marking is present, on all of the 12 main rotor shaft nut bolt

heads, no further inspection is required. Perform steps "o" through "t" of this paragraph.

(2)

If only the letter "M" is present on any one of the 12 main rotor mast nut bolt heads continue as follows.

Remove bolts holding the lower lockring to the main rotor shaft nut. Remove lockring. Inspect lockring for

missing rollpins from bushings or damaged bushings. Repair as necessary (TM 1-1500-204-23).

CAUTION

Do not remove more than one main rotor shaft nut bolt at a time. If more than one suspect bolt is

found, remove, replace, and retorque each bolt individually before replacing the next bolt.

Loosen and remove one suspect bolt from the main rotor shaft nut.